ON THE FOSSIL PIIYLLOrODA OF THE rAL.tOZOIC BOCKS. 



91 



but it is rather wider than long (oblatcly circular), and it has a very 

 wide and deep notch. 



' about 7 linos ( ,^ 

 and concentricallv 



4. Aptychoims rjlahra, H. Woodward, 1872. ' Sixth Report on Fossil 

 Crustacea, Report IBrit. Assoc, for 1H72,' p. 1^23 ; ' Geol. Mag.' vol. \. 

 (1872) p. 5G5. 



Tliis is an almost circular shield when perfect, 

 inch) in diameter,' with a wide and deep notch, 

 markt;d. It is like A. Wilsoni in general appearance, but is smaller and 

 <lifferent in proportions, having a relatively larger notch. It is also near 

 io the discoidal forms of A. prima, Barrando (var. secnnda). It is from 

 the Buckholm beds of the Gala group, Meigle, Galashiels, Dumfries. 

 About 18 mm. in diameter ; nuchal suture sloping at an angle of 50°. 



It may be the same as Gucullella angulata, Daily, ' Explan. Sheet 13"), 

 Geol. Surv. Ireland,' 18G0, p. 13, fig. 4 (woodcut). From the Lower 

 Silurian; Cloncannon, co. Tipporary. 



Specimens closely resembling A. glabra have been noticed and figured 

 by Mr. Dairon in the ' Trans. Geol. Soc. Glasgow,' vol. vii. (1883), 

 p. 177, pi. 7, figs. 31 and 34, from the Mofl'at Shales. 



5. Aptychopsis, sp. 



A single lefthand portion of the shield of an Aptijchopsis iu black 

 shale is preserved in the British Museum, unfortunately without locality, 

 which may belong to a distinct species. It has the usual cUiptico- 

 triangular shape of these separate moieties, but it is relatively broad in 

 front, with its anterior angle rounded, and the slope of the nuchal suture 

 is at about 35°, which makes a low wide cephalic notch. It has delicate 

 concentric lines, and very delicate radiating ruguhr (besides radiate lines 

 due to breakage under pressure). Jt measured, when perfect, about 27 

 by 25 mm. 



G. Ajttijchopsiii, sp. 



In the Museum of Practical Geology, London, are five specimens of an 

 Aptyr.hpsis, from the Cambrian slaty or schistose strata (known as 

 Tremadoc Slates) at Garth, near Portmadoc, North Wales. They consist 

 of elliptico-triangular moieties of an ohowaiG ApfyrJiopsis Hh'ni\(i in difl'erent 

 states of preservation. The apex of the notch is above the centre of the 

 test (unless altered bj pressure), and its slope is at abont 50". The out- 

 line of the whole tripartite shield would be broad obovato. Concentric lines 

 are faintly marked. The shape was probably (when perfect) broader than 

 the long foi'ms of Barrande's A. frlma. It approaches A. Lnpu-nrtlu also 

 in outline, but it is not quite so lull in the posterior curv'c, though larger 

 altogether —probably 82 mm. long by 30 mm. broad. 



7. AphjcJiopals Sailer!, H. Woodward, 18H2. 'Geol. Mag.' Dec. 2, 

 vol. ix. p. 389, t. 9, tig. 17; 



This distinctly marked bpecies had an ovate outline when perfect, 

 broadest in the hinder half: nuclial suture sloping at about 45°, its apex 

 reaching back a little more than a fourth of the whole length of the test. 

 Length about 35 mm., width 2G mm. 



Upper Silurian (Wenlock Shale), at Pencarreg, Caermarthenshire, 

 South Wales. 



